In the past several years, as interception and penetration technologies have multiplied, information assets have become increasingly vulnerable to interception while in transit across untrusted networks between the intended parties. The increasing prevalence of digital communications systems has led to the widespread use of digital encryption systems by governments and enterprises concerned with communications security. These systems have taken several forms, from data Virtual Private Networks (VPN), to secure voice/data terminals.
Enterprises are communicating using voice, fax, data modem, and video across the untrusted Public Switched Telephone Network (PSTN). Unfortunately, whereas a data VPN uses automated encryption and tunneling processes to protect information traveling over the Internet, a data VPN is not designed to protect voice, fax, modem, and video calls over the untrusted PSTN. This deficiency leaves solutions for creating safe tunnels through the PSTN to be primarily manual, requiring user participation at both ends to make a call secure (e.g., with the use of secure voice/data terminals, such as Secure Telephone Units (STU-IIIs), Secure Telephone Equipment (STE), and hand-held telephony encryption devices).
Additionally, secure voice/data terminals are point-to-point devices securing only one end-user station per device; so secure voice/data terminals cannot protect the vast majority of calls occurring between users who do not have access to the equipment. And although there may be policies that specifically prohibit it, sensitive material can be inadvertently discussed on non-secure phones and thereby distributed across the untrusted PSTN.
Secure voice/data terminals cannot implement an enterprise-wide, multi-tiered policy-based enforcement of a corporate security policy, establishing a basic security structure across an enterprise, dictated from the top of the tier downward. Neither can secure voice/data terminals implement an enterprise-wide, multi-tiered policy-based enforcement of selective event logging and consolidated reporting (i.e., multi-tiered policy-based security event notification) to be relayed up the tier.
Lastly, secure voice/data terminals cannot provide call event logs detailing information about secure calls. Therefore, a consolidated detailed or summary report of a plurality of call event logs can not be produced for use by security personnel and management in assessing the organization's security posture.
Clearly, there is a need for a system and method to provide secure access across the untrusted PSTN through telephony resources that can be initiated by a security policy defining actions to be taken based upon one or more attributes of the call, providing secured communications operating as a data call at 64 Kbps, with automatic adjustment to circuits operating at slower transfer rates, and providing multi-tiered policy-based enforcement capabilities, multi-tiered policy-based security event notification capabilities, and visibility into security events.
As used herein, the following terms carry the connotations described below:                Data VPN is understood to refer to a shared or public packet data network wherein privacy and security issues are mitigated through the use of a combination of authentication, encryption, and tunneling.        Tunneling is understood to refer to provision of a secure, temporary path over an Internet Protocol (IP)-based network by encapsulating encrypted data inside an IP packet for secure transmission across an inherently insecure IP network, such as the Internet.        Secure is understood to refer to the use of encryption to provide telecommunications privacy and security between two devices across an untrusted network (as discussed herein and specifically with reference to FIGS. 1, 11A-11D, 12, 13A-13E, and 16); or the result thereof.        Data call is understood to refer to a call using a bearer service that is circuit mode, with information transfer rates such as 64 Kbps, or 64 Kbps adapted to 56 Kbps, that uses unrestricted or restricted digital information transfer capability. For simplicity, the explanations herein deal with only unrestricted digital information at 64 Kbps and unrestricted digital information at 64 Kbps adapted to 56 Kbps, referred to as “data at 64 Kbps” and “data at 56 Kbps”, respectively.        Voice call is understood to refer to a call using a bearer service that is circuit mode, with speech or 3.1 kHz audio information transfer capability, and user information layer 1 protocol G.711 mu-law or A-law.        64K data secure mode is understood to refer to the administrator-allowable secure mode whereby the present invention autonomously encrypts and transmits as a 64 Kbps data call either: (1) a data call requiring a transfer rate less than 64 Kbps, or (2) a voice call; the circuit for which is requested by the present invention in accordance with the security policy.        56K data secure mode is understood to refer to the administrator-allowable secure mode whereby the present invention autonomously encrypts and transmits as a 56 Kbps data call either: (1) a data call requiring a transfer rate less than 64 Kbps, or (2) a voice call; the circuit for which is requested by the present invention in accordance with the security policy. Although administrator-allowable data secure modes with other transfer rates may be used, for simplicity, the explanations herein deal with data secure modes at 64 Kbps and 56 Kbps.        56K voice secure mode is understood to refer to the administrator-allowable secure mode whereby the present invention autonomously encrypts and transmits as a voice call with a transfer rate of 56 Kbps either: (1) a data call requiring a transfer rate less than 64 Kbps, or (2) a voice call; the circuit for which is requested by the present invention in accordance with the security policy. Although administrator-allowable voice secure modes with other transfer rates may be used, for simplicity, the explanations herein deal with voice secure modes at 56 Kbps, 48 Kbps, 40 Kbps, 32 Kbps, and 24 Kbps, referred to as either “56K voice secure mode”, “48K voice secure mode”, etc.; or “voice at 56 Kbps”, “voice at 48 Kbps”, etc.        